1. Field of the Invention
The present invention relates to a projector of a field sequential color type and a method of controlling alight source for use with the projector.
2. Description of the Related Art
In the past, in meetings or presentations projectors are used which convert an image signal received from an image supply device such as a computer to projection light, which is then magnified and projected onto a screen or a white board. Such projectors include the ones of a type called a field sequential color type which is capable of projecting a color image. In a projector of such type, a color wheel of red (R), green (G) and blue (B) filter sections arranged therein in the rotating direction thereof is rotated, and light from a light source is caused to passthrough the R, G and B sections sequentially, thereby producing corresponding colored light. These light are then caused to enter liquid crystal or a display device such as a micromirror array, thereby displaying and projecting a full color image.
Published Unexamined Japanese Patent Application 2004-151650 discloses a projector which does not produce R, G and B light from a single light source, but uses a light source of three different color (R, G and B) LEDs (Light Emitting Diodes) which are switched on sequentially in a time-divisional manner in a period. The Application also discloses that if the switch-on time of the green LED is set longer than those of the red and blue LEDs and a light flux quantity of the green light is set to 60-80 percent of the whole light flux quantity, a white projected image will be obtained.
Although this projector can provide a white projected image, the switch-on time of each color light of the light source is fixed in a light emission period of the light source. Thus, there is naturally a limit to improvement of the quality of the projected images.